Much debate has focused on whether or not patients with chest pain despite normal epicardial coronary arteries truly experience myocardial ischemia. Fifty such patients underwent both a pacing coronary flow study and rest and exercise gated blood-pool scintigraphy. During atrial pacing those patients developing their typical chest pain, especially after ergonovine administsration, demonstrated apparent abnormal vasodilator reserve of the coronary circulation, associated with mechanical and metabolic evidence of ischemia. The 40 patients with abnormal vasodilator reserve demonstrated reduced rest and exercise left ventricular ejection fraction by gated blood pool scintigraphy, and half the patients in this group demonstrated exercise-induced wall motion afnormalities. These patients also manifested impaired diastolic filling at rest. Thus, patients with chest pain due to abnormal vasocilator reserve demonstrate abnormalities of left ventricular systolic and diastolic function suggestive of myocardial ischemia.